Retractable sewing machine cutting mechanism

ABSTRACT

An extensible and retractable carrier is operably mounted at a cutting station in a feed path of material to be stitched and cut, and a knife is mounted on the carrier for movement into and out of the feed path of the material. The knife is pivotally supported on the carrier for independent swinging movement about an axis generally perpendicular to the feed path of the material, and operating means are provided for automatically swinging the knife in an opposite angular direction after each cutting operation for varying the angle of cut during alternate cutting operations.

United 1 Rockerath RETRACTABLE SEWING MACHINE CUTTING MECHANISM [75] Inventor: John L. Rockerath, Utica, NY. [73] Assignee: Jetsew Inc., Barneveld, NY. 1 [22] Filed: June 16, 1971 [21] Appl. No.: 153,664

[52] US. Cl. 112/130, l12/121.11 [51] Int. Cl D05b 37/04 [58] Field 01 Search ll2/12l.ll, 121.15,

[56] References Cited UNITED STATES PATENTS 3,696,765 10/1972 Bernewasser l12/12l.12

45} Oct. 9, 1973 Primary Examiner-H. Hampton Hunter Attorney-John M. Prutzman et a1.

[5 7] ABSTRACT An extensible and retractable carrier is operably mounted at a cutting station in a feed path of material to be stitched and cut, and a knife is mounted on the carrier for movement into and out of the feed path of the material. The knife is pivotally supported on the carrier for independent swinging movement about an axis generally perpendicular to the feed path of the material, and operating means are provided for automatically swinging the knife in an opposite angular direction after each cutting operation for varying the angle of cut during alternate cutting operations.

20 Claims, 5 Drawing Figures PATENIEDUEI 91m SHEEI 10? 3 I NVENTOR JOHN L. ROCKERATH ATTORNEYS PATENTEDUET n 3.763.800

' SHEU 20F 3 PATENTEU 91975 I sum 3 [IF 3 RETRACTABLE SEWING MACHINE CUTTING MECHANISM This invention generally relates to sewing machines and particularly concerns an improved cutting mechanism for a sewing machine.

A primary object of this invention is to provide an improved sewing machine cutting mechanism capable of automatically varying the angle at which material is cut on alternate cutting operations.

Another object of this invention is to provide a cutting mechanism of the above-described type particularly suited to be incorporated in either new or existing sewing machines and which is automatically operated in timed relation to the passage of material along its feed path in an automated sewing and cutting operation.

A further object of this invention is to provide such a cutting mechanism usable in a sewing machine for cutting material at different predetermined angles while virtually eliminating any possibility of buckling of the material and undesired jamming of the machine even thoughmaterial of different sizes and varying layers are being fed through the machine to be stitched and cut.

Still another object is to provide an improved belt feeding system for positive control of material being fed in a sewing machine of the above-described type.

Other objects will be inpart obvious and in part pointed out in more detail hereinafter.

A better understanding of the objects, advantages, features, properties and relationships of the invention will be obtained from the following detailed description and accompanying drawings which set forth an illustrative embodiment and is indicative of the way in which the principle of the invention is employed.

IN THE DRAWINGS:

FIG. 1 isa side view, partly broken away, schematically illustrating a sewing machine incorporating this invention;

FIG. 2 is a plan view, partly brokenaway, of the machine of FIG. 1 showing material being fed along its feed path to the machine;

FIG. 3 is an enlarged isometric view, partly broken away, of a cutting mechanism incorporated in the machine;

FIG. 4 is an enlarged bottom view, partly broken away, of the cutting mechanism of FIG. 3; and

FIG. 5 is a view, partly broken away, schematically illustrating a typical fluid control circuit for the cutting mechanism.

' nism 28 incorporated in the machine of this inven- Referring to the drawings in detail wherein a preferred embodiment of this invention is illustrated, a

sewing machine 10 is shown having a conventional sewing machine head 12 supporting a needle bar 14 and presser foot 16 above a support plate 18 which will be understood to be secured to a conventional machine frame, not shown.

Material which if desired may be of a varying number of layers) such as the illustrated shirt front 20 is fed along a feed path in the direction of the arrow in FIG. 2 to be stitched and cut. The feed path is established in part by work supporting surfaces such as at 22. For positively controlling the advance of material, laterally spaced pairs of narrow, opposed, upper and lower highspeed conveyor belts or tapes 24, 26 are provided for tion and shown for illustrative purposes in downstream relation to the stitching station.

The. sewing machine head 12 may be operated by suitable automaticcontrols, not shown, in accordance with conventional techniques to apply a suitable line of stitching to the material 20 passing through the stitching station, and thereafter the stitching operation may be automatically interrupted upon passage of the trailing edge of the material through the head 12 of the ma chine l0.

Suitable photoelectric devices such as at 30 may be provided for actuating a cutting operation at the cutting station responsive, e.g., to the leading edge of the material passing into and out of the cutting station. It will be sufficient for an understanding of this invention to state that an output signal for initiating automatic operation of the cutting mechanism 28 may be produced by interrupting light which normally falls between the tapes 24, 26 from overhead light sources such as at 32 onto underlying photocells such as at 34 for cutting leading and trailing edge portions, e.g., of the material in timed relation to its passage through the cutting station.

The cutting mechanism 28 has a frame 36 (FIG. 3) suitably secured to the machine frame, not shown, and a cutting means illustrated as a scissors type knife assembly or knife 40 is operably mounted on the frame 36 at a height corresponding to the feed path of the material. The knife 40 is shown (FIGS; 1 and 2) located in noninterfering relation to the upper and lower tape systems in a gap within the feed path of the material which is established by offset idler rollers 37 and 38 about which the upper tapes 24 and lower tapes 26 are respectively trained. Thus, as the material 20 is fed between the tapes 24, 26, the upper and lower tape systems may be driven by a common variable speed drive, not shown, or by any other type driving arrangement which would rotate the feed rollers, such as at 41, at a desired rotary speed. The actuation of the knife 40 by the photoelectric material sensing devices 30 is accordingly synchronized with the relative speeds of the tapes 24, 26 and the corresponding speed of travel of the portions of the material 20 to be cut.

The illustrated knife 40 includes a fixed blade 48, secured to a knife support arm 50, and a relatively movable blade 52 supported for pivotal movement about a horizontal pivot shaft 54 fixed to a housing 56 on the arm 50. An outer free end of the movable blade 52 is thus mounted for movement in a vertical plane toward and away from the fixed blade 48 between a relatively closed position and a relatively open position best seen in FIG. 3. The knife 40 may be desirably actuated by any suitable means but in the illustrated embodiment, its movable blade 52 will be understood to be operated by a piston, not shown, of a power cylinder 58 illus-, trated as a standard air cylinder secured on the support arm 50 to extend rearwardly of its housing 56. When compressed air is introduced to the cylinder 58, its piston is thrust forward to move blade 52 into closed position to effect an excellent cutting action. Upon exhausting air from cylinder 58, its piston will be understood to be spring returned to move blade 52 back into, open position.

For selectively varying the angle of cut of the material 20 being fed through the machine in accordance with this invention, while atthe same time ensuring that the depth of cut relative to a side edge E of the material remains constant regardless of the angle of cut, the knife 40 is supported on arm 50 for swinging movement about a vertical axis established by an upright pivot shaft 60 fixed to arm 50 and extending downwardly from its extreme forward end. The pivot shaft 60 is mounted for rotation on an extreme forward end of an elongated, horizontally disposed slide or carrier 62 with the free ends of the knife blades 48, 52 positioned in substantially coaxial alignment with the axis of pivot shaft 60.

So that the knife 40 may be immediately retracted after a cutting operation, to minimize any undesired buckling of the material 20, and thereafter be repositioned adjacent the feed path of the material for a subsequent cutting operation, the carrier 62 is mounted for linear reciprocating movements toward and away from the feed path of the material. Carrier 62 is shown having laterally extending lugs such as at 64 and 66 respectively, supported and guided for movement along a pair of horizontally disposed carrier rods 68 and 70'fixed to the frame 36 of the cutting mechanism 28 on opposite sides of the carrier 62.

In the specifically illustrated embodiment of this invention, carrier 62 is advanced and retracted with a reciprocating motion by extension and retraction of a piston rod 72 of a conventional double-acting air cylinder 74 rigidly secured in a horizontal position to the frame 36. The piston rod 72 is connected by a fastener 76 to a thrust plate 78 intermediate the ends of carrier 62. If desired, the stroke length of piston rod 72 may be adjusted in accordance with conventional techniques for readily varying the extent to which the knife 40 is positioned in the feed path of the material to be cut and thereby to vary the depth of cut.

By virtue of the above-described structure, the knife 40 not only is supported for reciprocating movement with the carrier 62 into and out of the feed path of the material but is also desirably supported for swinging movements independently of the carrier 62 in a horizontal plane in opposite angular directions about pivot shaft 60.

To provide such swinging movements of the knife 40, a pair of horizontally extending, vertically spaced, switching arms 80, 82 are rigidly fixed in angularly offset relation to one another on a lower end portion of pivot shaft 60 extending below carrier 62, and arm 80 is shown drivingly connected to a piston rod 84 of a standard double-acting air cylinder 86. Cylinder 86 is mounted below frame 36 on an underlying support plate 88 secured to the bottom of the carrier 62 and extending laterally outwardly therefrom through a cutout portion 90 of frame 36. Both arms 80, 82 are accordingly moved in unison in opposite angular directions responsive to extension and retraction of piston rod 84, wherby pivot shaft 60 and knife 40 are swung through an angular displacement established by appropriate limit stops.

The angular displacement of knife 40 as shown in FIGS. 2 and 5 extends through an angle 0 from a straight cutting position of the knife 40 (illustrated infull lines) to an inclined cutting position (represented by broken lines). While the stroke length of the piston rod 84 obviously may be adjusted by any suitable means, the preferred embodiment utilizes cylinder 86 as a stop for the piston rod 84 in its fully extended position to establish a limit position for knife 40 in an inclined cutting position. A limit position in the opposite angular direction is shown in FIG. 4 provided by fastener 92 threadably connected to the underlying cyilnder support plate 88 and secured in an adjusted position by a lock nut 94, whereby retraction of the piston rod 84 repeatedly locates knife 40 in a second selected position relative to the material such as the illustrated straight cutting position of the knife 40.

When it is desired to sequentially cut material being fed through the cutting station at varying angles of cut, by virtue of the above-described construction, the sewing machine cutting mechanism 28 of this invention is particularly suited for a completely automated sequence of operations governed by movement of carrier 62.

For this purpose, a suitable fluid control circuit is provided as best seen in FIG. 5 wherein USA Standard fluid power graphic symbols are employed. Compressed air from an external source, not shown, is supplied through fluid supply lines 96, 98 to a pair of pilot actuated, two-position, four-way, five ported pneumatic signal control valves 100, 102 respectively controlling operation of air cylinders 74, 86 for longitudinally positioning the carrier 62 and angularly positioning the knife 40. Control valves 100, 102 each have cylinder ports connected through suitable tubing 104, 106 and 108, 110 to opposite ends of the double-acting cylinders 74 and 86. In FIG. 5 the cylinder 74 (for reciprocating the carrier 62) is shown in a normal extended position, and the cylinder 86 (for adjusting the angular position of the knife 40) is shown in a normal retracted position to locate knife 40 in a first angular cutting position which in the preferred embodiment is shown as being its straight cutting position. As previously described, knife 40 is normally open when its power cylinder 58 is connected to exhaust as seen in FIG. 5, wherein cylinder 58 is shown connected by tubing 112 to a common outlet passage 114 leading to a twoposition, three-way solenoid operated valve 116.

When carrier 62 is in its normal extended position with knife 40 normally open and in its straight cutting position, the axis of pivot shaft and, accordingly, the free ends of blades 48, 52 are positioned at a preselected depth of cut in the aforementioned gap in the feed path of the material 20, preferably in line with photoelectric devices 30 which will be understood to control actuation of the solenoid operated valve 116 in timed relation to passage of material 20 past knife 40.

Upon photoelectric actuation of the solenoid operated valve 116 responsive to the leading edge of material, 20 entering the cutting station, compressed air from a fluid supply line 118 is introduced into power cylinder 58, closing knife blade 52 and severing the leading edge of the material 20 along a line of cut as shown by broken lines 140. Simultaneously, the carrier positioning control valve is actuated via a fluid line 120 communicating with the common outlet passage 114, whereupon the air connections to cylinder 74 are reversed. Piston rod 72 is then automatically retracted and carrier 62 is immediately withdrawn away from the feed path of the material 20 into a retracted inoperative position, thereby minimizing any possibility of buckling of material passing through the cutting station and to effectively minimize any shutting down of the machine due to jamming.

Withdrawal of carrier 62 automatically actuates a lever operated two-position, three-way switching valve 122 connected by a line 124 to the air supply to pressurize a fluid line 126 leading to a pilot actuator of solenoid operated valve 116. Valve 116 thereby shifts into its normal position and is reconditioned for subsequent photoelectric actuation while also venting power cylinder 58 to permit its piston rod to be spring returned to ensure that blades 48, 52 are open prior to knife 40 being power returned into the feed path of the material when carrier 62 is repositioned in its normal extended position. In this regard, actuation of switching valve 122 simultaneously shifts carrier positioning control valve 100, again reversing its fluid connections to cylinder 74 and extending its piston rod 72 to automatically power return carrier 62 into normal extended position in preparation for the next cutting operation.

During retraction of carrier 62, the angularly offset arms 80 and 82 alternately trigger lever operated twoposition, three-way pilot actuating valves 128 and 130. Valves 128 and 130 have supply lines' 132 and 134 leading to the air supply and which are respectively connected upon valve actuation to lines-136 and 138 leadingto pilot actuators of the knife positioning control valve 102.

Accordingly, during the above-described retraction of carrier 62 after knife 40 has made a straight out in the leading edge of the material as shown by the broken lines 140, arm 80 triggers pilot actuating valve 128 to shift knife positioning control valve 102, reversing the connections to the double-acting air cylinder 86 to extend its piston'rod 84. Extension of piston rod 84 rotates arms 80, 82 and knife 40 via the interconnecting pivot shaft 60 through a preselected angle determined by the previously described limit stops to position knife 40 in inclined cutting position. This angular rotation occurs about the pivotal axis of the shaft 60 which is thereafterautomatically relocated in alignment with the scan line of the photoelectric devices 30 in the path of movement of the material 20.

Asthe trailing edge of the material passing into the cutting station is sensed by the downstream photoelectric device 30, e.g., responsive to the presence of the leading edgeof the material, the solenoid operated valve 116 is again actuated to cut the trailing edge of the material along an inclined line of cut as shown by the broken lines 142, and to retract carrier 62 in accordance with the above-described sequence of operations. However, it will be understood that such subsequent retracting movement of carrier 62 then triggers the other pilot actuating valve 130 by means of arm 82, due to the extended position of the piston rod 84, whereby the knife positioning control valve 102 is again shifted to automatically return knife 40 to its original straight cutting position in readiness for cutting a leading edge of a following piece of material.

The speed at which cylinders 100 and 102 travel may be selectively adjusted to correspond with the passage of material past the cutting station by suitable variable flow restriction valves such as shown at 144, 146 installed on exhaust ports of valves 100, 102.

A sewing machine cutting mechanism constructed in accordance with this invention is particularly suited to be adapted for a completely automated sequence of operations whereby varying angles of cuts limited to a predetermined depth of cut may be selectively adjusted and sequentially effected by a suitable knife in a high speed production operation. Undesired buckling of material is effectively minimized by substantially instantaneous retraction of the knife upon its being operated to cut the material passing through the cutting station. Either new or existing sewing machines may be readily adapted to incorporate the cutting mechanism herein described which is of relatively simplified but rugged construction and which is economical to both manufacture and assembly to effect efficient combination sewing and cutting operations characterized by a significantly reduced required time cycle.

As will be apparent to persons skilled in the art, various modifications, adaptations and variations of the foregoing specific disclosure can be made without departing from the teachings of the present invention.

I claim:

1. In a sewing machine having a cutting station in a feed path of material to be sewed, a cutting mechanism comprising a frame, a knife carrier, mounting means supporting the knife carrier on the frame for reciprocating movement toward and away from the feed path of the material between a normal extended position and a retracted inoperative position, a scissors-type knife operatively mounted on the knife carrier for reciprocable linear movement therewith, the knife including a movable blade supported for swinging movement between a normalrelatively open position and a relatively closed position for severing material at the cutting station with the knife carrier in its normal extended position, the knife being further supportedon the knife carrier for pivotal movement about an axis generally perpendicular to the feed path of the material for varying the angle of the knife relative to the material for a cutting operation, and knife positioning means for angularly rotating the knife about said pivotal axis and positioning it in a selectedangular positionto the feed path of the material for a cutting operation, the movable knife blade being supported for swinging movement about an axis in normal relation to said pivotal axis of said knife, the movable blade having afree swinging end establishing the depth of cut of the material, the free swinging end of the movable blade in its said relatively closed position being positioned in substantial coaxial alignment with said pivotal axis of said knife regardless of the angular position of the knife relative to the feed path of the material.

2. The cutting mechanism of claim 1 further including power operated means for moving the knife to relatively closed position, actuating means for actuating the power operated means in response to passage of material through the cutting station, and driving means operably connected to the knife and responsive to the actuating means for automatically retracting the knife awayfrom the feed path of the material substantially simultaneously with movement of the knife into relatively closed position.

3. The cutting mechanism of claim 1 further including stop means supported on the frame and establishing first and second extreme limit positions of pivotal movement of the knife in opposite angular directions for varying its angle of cut.

4. The cutting mechanism of claim 3 wherein the stop means includes an adjustable stop for varying the angular orientation of the knife for a cutting operation in at least one of its said first and second extreme limit positions.

5. The cutting mechanism of claim 1 wherein the knife is being pivotally supported on the carrier for rotation about said pivotal axis by said knife positioning means and for reciprocation with the carrier into and out of the feed path of the material, carrier positioning means drivingly connected to the carrier for reciprocating the carrier and the knife carried thereby between said normal extended position and said retracted inoperative position, sensing means for sensing passage of material through the cutting station, and operating means automatically actuatable by the sensing means for moving the knife to its relatively closed position in timed relation to passage of material through the cutting station, the carrier positioning means being automatically actuatable by the sensing means to retract the carrier from its normal extended position substantially simultaneously with movement of the knife into its relatively closed position during each cutting operation.

6. The cutting mechanism of claim 5 wherein the operating means for the knife automatically repositions it in its normal relatively open position after each cutting operation but prior to the carrier being returned to its normal extended position 7. The cutting mechanism of claim 5 wherein the knife positioning means is actuatable by the carrier during its reciprocating movement to alternately rotate the knife automatically into first and second angular cutting positions forsuccessive cutting operations.

8. The cutting mechanism of claim 5 wherein the carrier positioning means further includes an actuating cylinder secured to the frame and an extensible and retractable piston rod connected to the carrier and operated by the cylinder for reciprocating the carrier between its normal extended position and its retracted inoperative position.

9. The cutting mechanism of claim 8 further including a pilot actuated control valve for operating the actuating cylinder, a pilot actuating valve adjacent the carrier, and a solenoid operated valve actuated by the sensing means, the carrier being reciprocated between its normal extended position and retracted inoperative position by successive automatic actuation of the solenoid operated valve by the sensing means and actuation of the pilot actuated control valve by carrier engagement therewith during a retracting movement of the carrier.

10. The cutting mechanism of claim 1 wherein the feed path of the material is contained in a generally horizontal plane, wherein the frame includes a knife carrier mounted thereon for reciprocating movement laterally toward and away from the feed path respec- '55 tively between a normal extended position and a re tracted inoperative position, and wherein a knife support is provided having a vertical pivot shaft rotatably supported on the carrier, the knife including a movable blade operatively mounted on the knife support for movement about a generally horizontal pivot axis, the knife positioning means including an actuating cylinder secured to thecarrier and having a piston rod operated by the cylinder to respectively extend and retract the piston rod after alternate cutting operations in response to reciprocating movement of the carrier, and a driving connection between the piston rod and the pivot shaft for alternately swinging the knife to first and second angular cutting positions as the piston rod is extended or retracted by the cylinder.

11. The cutting mechanism of claim 10 wherein the driving connection between the piston rod and pivot shaft includes a pair of arms fixed to the pivot shaft with at least one of the arms being connected to the piston rod, and wherein first and second cylinder operating control means are disposed on the frame for engagement respectively with the arms, the first and second control means each being engageable with its respective arm after alternate cutting operations for respectively extending and retracting the cylinder to automatically position the knife in said first and second angular positions for successive cutting operations.

12. The cutting mechanism of claim 11 wherein the knife positioning means further includes fluid control means having a pilot actuated fluid control valve for operating the-actuating cylinder, the fluid control valve being alternately actuated by said first and second-cylinder operating control means after successive cutting operations for automatically respositioning the knife in its opposite cutting position for varying the angle of cut on each successive cutting operation.

13. In a sewing machine having a cutting station in a feed path of material to be sewed, a cutting mechanism comprising a frame, a carrier, mounting means supporting the carrier on the frame for reciprocating linear movement toward and away from the cutting station between a normal extended position and a retracted inoperative position, cutting means operatively mounted on the carrier for linear movement therewith into and out of the feed path of the material for severing the material in a cutting operation, the cutting means being further supported on the carrier for pivotal movement about an axis in substantially perpendicular relation to the feed path of the material for varying the angle of the cutting means relative to the material for a cutting operation, and positioning means for angularly rotating the cutting means about said pivotal axis between first and second angular cutting positions, the positioning means being actuatable by the carrier during its reciprocating movement to alternately rotate the cutting means into first and second angular cutting positions for successive cutting operations.

14. The cutting mechanism of claim 13 wherein the cutting means comprises a pair of cooperating blades mounted on the carrier, the blades being operable for relative pivotal movement between a normally open position and a closed cutting position.

15. The cutting mechanism of claim 14 wherein the carrier bodily moves the cutting blades mounted thereon into and out of the feed path of the material, blade operating means for automatically pivoting the blades from said normally open to closed cutting positions in times relation to passage of material along its feed path through the cutting station when the carrier is in its normal position, and carrier positioning means for automatically retracting the carrier from its said normal extended position upon movement of the blades into closed cutting position.

16. The cutting mechanism of claim 15 wherein the blade operating means automatically move the blades to relatively open position after each cutting operation but prior to the carrier being repositioned in its said normal extended position for the next cutting operation.

17. The machine of claim 13 further including a first double-acting power cylinder for extending and retracting the carrier, a second double-acting power cylinde'r for swinging'the cutting means about said pivot axis in opposite angular directions during alternate cutting operations, and control means including fluid valve means for selectively operating the double-acting power cylinders in timed relation to terial along the feed path.

18. The cutting mechanism of claim 13 further including positioning means for controlling angular orientation of the cutting means, the positioning means being drivingly connected to the cutting means for pivoting the same about said pivotal axis alternately in opposite angular directions after successive cutting operations to automatically position the cutting means in selected first and second angular positions relative to the material being fed through the cutting station for automatically severing the material at different angles on alternate cutting operations.

19. The cutting mechanism of claim 18 wherein operation of the positioning means is controlled by movement of the carrier.

20. In a sewing machine having a cutting station in a feed path of material to be sewed, a cutting mechanism comprising a frame, a carrier, mounting means supporting the carrier on the frame for reciprocating linear passage of the mamovement toward and away from the cutting station between a normal extended position and a retracted inoperative position, cutting means operatively mounted on the carrier for linear movement therewith into and out of the feed path of the material for severing the material in a cutting operation, the cutting means being further supported on the carrier for pivotal movement about an axis in substantially perpendicular relation to the feed path of the material for varying the angle of the cutting means relative to the material for a cutting operation, the cutting means including a pair of cooperating blades mounted on the carrier, the blades being operable for relative pivotal movement between a normally open position and a closed cutting position, the cutting blades being mounted for relative swinging movement toward and away from one another about an axis generally perpendicular to said first pivotal axis, the cutting blades having free ends supported on the carrier in substantial coaxial alignment with said first pivotal axis, said carrier in its normal extended position locating said first pivotal axis and said free ends of the cutting blades in a predetermined position within the feed path of the material regardless of the angular orientation of the cutting means about its said first pivotal axis relative to the material. 

1. In a sewing machine having a cutting station in a feed path of material to be sewed, a cutting mechanism comprising a frame, a knife carrier, mounting means supporting the knife carrier on the frame for reciprocating movement toward and away from the feed path of the material between a normal extended position and a retracted inoperative position, a scissors-type knife operatively mounted on the knife carrier for reciprocable linear movement therewith, the knife including a movable blade supported for swinging movement between a normal relatively open position and a relatively closed position for severing material at the cutting station with the knife carrier in its normal extended position, the knife being further supported on the knife carrier for pivotal movement about an axis generally perpendicular to the feed path of the material for varying the angle of the knife relative to the material for a cutting operation, and knife positioning means for angularly rotating the knife about said pivotal axis and positioning it in a selected angular position to the feed path of the material for a cutTing operation, the movable knife blade being supported for swinging movement about an axis in normal relation to said pivotal axis of said knife, the movable blade having a free swinging end establishing the depth of cut of the material, the free swinging end of the movable blade in its said relatively closed position being positioned in substantial coaxial alignment with said pivotal axis of said knife regardless of the angular position of the knife relative to the feed path of the material.
 2. The cutting mechanism of claim 1 further including power operated means for moving the knife to relatively closed position, actuating means for actuating the power operated means in response to passage of material through the cutting station, and driving means operably connected to the knife and responsive to the actuating means for automatically retracting the knife away from the feed path of the material substantially simultaneously with movement of the knife into relatively closed position.
 3. The cutting mechanism of claim 1 further including stop means supported on the frame and establishing first and second extreme limit positions of pivotal movement of the knife in opposite angular directions for varying its angle of cut.
 4. The cutting mechanism of claim 3 wherein the stop means includes an adjustable stop for varying the angular orientation of the knife for a cutting operation in at least one of its said first and second extreme limit positions.
 5. The cutting mechanism of claim 1 wherein the knife is being pivotally supported on the carrier for rotation about said pivotal axis by said knife positioning means and for reciprocation with the carrier into and out of the feed path of the material, carrier positioning means drivingly connected to the carrier for reciprocating the carrier and the knife carried thereby between said normal extended position and said retracted inoperative position, sensing means for sensing passage of material through the cutting station, and operating means automatically actuatable by the sensing means for moving the knife to its relatively closed position in timed relation to passage of material through the cutting station, the carrier positioning means being automatically actuatable by the sensing means to retract the carrier from its normal extended position substantially simultaneously with movement of the knife into its relatively closed position during each cutting operation.
 6. The cutting mechanism of claim 5 wherein the operating means for the knife automatically repositions it in its normal relatively open position after each cutting operation but prior to the carrier being returned to its normal extended position.
 7. The cutting mechanism of claim 5 wherein the knife positioning means is actuatable by the carrier during its reciprocating movement to alternately rotate the knife automatically into first and second angular cutting positions for successive cutting operations.
 8. The cutting mechanism of claim 5 wherein the carrier positioning means further includes an actuating cylinder secured to the frame and an extensible and retractable piston rod connected to the carrier and operated by the cylinder for reciprocating the carrier between its normal extended position and its retracted inoperative position.
 9. The cutting mechanism of claim 8 further including a pilot actuated control valve for operating the actuating cylinder, a pilot actuating valve adjacent the carrier, and a solenoid operated valve actuated by the sensing means, the carrier being reciprocated between its normal extended position and retracted inoperative position by successive automatic actuation of the solenoid operated valve by the sensing means and actuation of the pilot actuated control valve by carrier engagement therewith during a retracting movement of the carrier.
 10. The cutting mechanism of claim 1 wherein the feed path of the material is contained in a generally horizontal plane, wherein the frame includes a knife caRrier mounted thereon for reciprocating movement laterally toward and away from the feed path respectively between a normal extended position and a retracted inoperative position, and wherein a knife support is provided having a vertical pivot shaft rotatably supported on the carrier, the knife including a movable blade operatively mounted on the knife support for movement about a generally horizontal pivot axis, the knife positioning means including an actuating cylinder secured to the carrier and having a piston rod operated by the cylinder to respectively extend and retract the piston rod after alternate cutting operations in response to reciprocating movement of the carrier, and a driving connection between the piston rod and the pivot shaft for alternately swinging the knife to first and second angular cutting positions as the piston rod is extended or retracted by the cylinder.
 11. The cutting mechanism of claim 10 wherein the driving connection between the piston rod and pivot shaft includes a pair of arms fixed to the pivot shaft with at least one of the arms being connected to the piston rod, and wherein first and second cylinder operating control means are disposed on the frame for engagement respectively with the arms, the first and second control means each being engageable with its respective arm after alternate cutting operations for respectively extending and retracting the cylinder to automatically position the knife in said first and second angular positions for successive cutting operations.
 12. The cutting mechanism of claim 11 wherein the knife positioning means further includes fluid control means having a pilot actuated fluid control valve for operating the actuating cylinder, the fluid control valve being alternately actuated by said first and second cylinder operating control means after successive cutting operations for automatically respositioning the knife in its opposite cutting position for varying the angle of cut on each successive cutting operation.
 13. In a sewing machine having a cutting station in a feed path of material to be sewed, a cutting mechanism comprising a frame, a carrier, mounting means supporting the carrier on the frame for reciprocating linear movement toward and away from the cutting station between a normal extended position and a retracted inoperative position, cutting means operatively mounted on the carrier for linear movement therewith into and out of the feed path of the material for severing the material in a cutting operation, the cutting means being further supported on the carrier for pivotal movement about an axis in substantially perpendicular relation to the feed path of the material for varying the angle of the cutting means relative to the material for a cutting operation, and positioning means for angularly rotating the cutting means about said pivotal axis between first and second angular cutting positions, the positioning means being actuatable by the carrier during its reciprocating movement to alternately rotate the cutting means into first and second angular cutting positions for successive cutting operations.
 14. The cutting mechanism of claim 13 wherein the cutting means comprises a pair of cooperating blades mounted on the carrier, the blades being operable for relative pivotal movement between a normally open position and a closed cutting position.
 15. The cutting mechanism of claim 14 wherein the carrier bodily moves the cutting blades mounted thereon into and out of the feed path of the material, blade operating means for automatically pivoting the blades from said normally open to closed cutting positions in times relation to passage of material along its feed path through the cutting station when the carrier is in its normal position, and carrier positioning means for automatically retracting the carrier from its said normal extended position upon movement of the blades into closed cutting position.
 16. The cutting mechanism of claim 15 wherein the blade operating means automatiCally move the blades to relatively open position after each cutting operation but prior to the carrier being repositioned in its said normal extended position for the next cutting operation.
 17. The machine of claim 13 further including a first double-acting power cylinder for extending and retracting the carrier, a second double-acting power cylinder for swinging the cutting means about said pivot axis in opposite angular directions during alternate cutting operations, and control means including fluid valve means for selectively operating the double-acting power cylinders in timed relation to passage of the material along the feed path.
 18. The cutting mechanism of claim 13 further including positioning means for controlling angular orientation of the cutting means, the positioning means being drivingly connected to the cutting means for pivoting the same about said pivotal axis alternately in opposite angular directions after successive cutting operations to automatically position the cutting means in selected first and second angular positions relative to the material being fed through the cutting station for automatically severing the material at different angles on alternate cutting operations.
 19. The cutting mechanism of claim 18 wherein operation of the positioning means is controlled by movement of the carrier.
 20. In a sewing machine having a cutting station in a feed path of material to be sewed, a cutting mechanism comprising a frame, a carrier, mounting means supporting the carrier on the frame for reciprocating linear movement toward and away from the cutting station between a normal extended position and a retracted inoperative position, cutting means operatively mounted on the carrier for linear movement therewith into and out of the feed path of the material for severing the material in a cutting operation, the cutting means being further supported on the carrier for pivotal movement about an axis in substantially perpendicular relation to the feed path of the material for varying the angle of the cutting means relative to the material for a cutting operation, the cutting means including a pair of cooperating blades mounted on the carrier, the blades being operable for relative pivotal movement between a normally open position and a closed cutting position, the cutting blades being mounted for relative swinging movement toward and away from one another about an axis generally perpendicular to said first pivotal axis, the cutting blades having free ends supported on the carrier in substantial coaxial alignment with said first pivotal axis, said carrier in its normal extended position locating said first pivotal axis and said free ends of the cutting blades in a predetermined position within the feed path of the material regardless of the angular orientation of the cutting means about its said first pivotal axis relative to the material. 